Medical Assessment of Children with Intellectual and Developmental Disabilities

Sandra L. Friedman, MD, MPH 
Section Head of Developmental-Behavior Pediatrics and Visiting Associate Professor,
Department of Pediatrics, University of Colorado Denver

Every day, Children's Hospital Colorado evaluates patients with a variety of developmental and neurobehavioral differences. Before patients undergo formal screening at Children's, there is an important role that parents and primary care providers play in identifying developmental difficulties. The American Academy of Pediatrics (AAP) has recommended that all children undergo formal, general screening for developmental problems at nine, 18, 24 and 30 months of age. More recently, the AAP also recommended that all children be formally screened for autism spectrum disorders at ages 18 and 24 months. Screening also needs to be performed if a child presents with concerns outside these intervals. Clinical judgment alone has been found to be insufficient to identify developmental difficulties; however parental concern does tend to be a positive predictor of some type of difficulty.

Certainly, if a child presents with developmental delays, referral needs to be made for more extensive diagnostic developmental testing, as well as for initiation of developmental services through Early Intervention for a child less than age three, or through the school system for children three years of age and older. While it is critical to initiate developmental services as soon as possible, it is also important to determine who needs a medical work-up and what type of medical assessment should be performed.

In determining what medical tests are needed, it is important to think about possible etiologic factors for a child's developmental problems. Potential insults on the developing brain can occur in the pre-, peri- and/or post-natal periods. These insults may be secondary to genetic, metabolic, toxins, infectious, traumatic, deprivation (such as nutritional or psychosocial) or idiopathic causes.

A working hypothesis about what causes a child's developmental problems informs the type of tests to be ordered. A thorough medical history should evaluate events from the prenatal period to the present time, developmental history and trajectory (e.g., slow and steady, plateau or regression of skills), family and social history. A comprehensive physical examination needs to evaluate growth parameters and patterns, evidence of dysmorphology, significant physical findings (e.g., enlarged liver, spleen, thyroid, etc.), and thorough neurological assessment, with particular emphasis on the presence and/or resolution of primitive reflexes, postural responses, asymmetries of muscle tone, reflexes or movement patterns.

There are a number of algorithms available to consider when trying to determine what tests should be obtained. Tests should be ordered judiciously, and performed in a step-wise fashion to evaluate etiology of a child's developmental problems. There are some variations in how different providers approach the medical work-up, with more than one way to carry out a comprehensive assessment. In all approaches, it is important that evaluations are performed in a systematic manner while closely following a patient. Referrals to specialists should be made when one gets to a point in which more input is needed or if there is a high index of suspicion for a unifying medical diagnosis that has not been identified with initial testing. All children with language disorders need to undergo tests of hearing acuity, even in the context of normal neonatal hearing tests. Visual screening should also be performed.

Step 1

If a child presents with a history or physical presentation suggestive of a specific disorder, then tests should initially target that particular diagnosis. These tests may include an MRI of the brain for a child with an abnormal head size, history of birth asphyxia, or asymmetric neurological examination. Specific genetic tests should be performed if presentation indicates a specific syndrome (e.g., Down syndrome, Fragile X). Neurophysiologic tests should be ordered for history or behaviors suggestive of seizures. Metabolic testing should be done on children with regression of developmental skills or prolonged recovery from acute illnesses. A lead level should be considered with history of pica and potential exposure to lead paint. Consideration should be given to checking thyroid function tests on children who are not growing well and basic hematologic tests for those with poor nutritional intake.

Step 2

If Step 1 is negative, or if etiology is unclear, then initial genetic testing should be performed. We are now ordering chromosomal microarray assays, which provide much more information than basic karyotype testing. If, however, insurance companies do not provide coverage for this type of testing, then high resolution chromosomal testing should be performed. Fragile X testing should also be considered, even for girls, unless the child has microcephaly.

Step 3

If Step 2 is negative, then consideration should be given to metabolic testing (e.g., plasma amino acids, urine organic acids, lactate, pyruvate, carnitine, mucopolysaccharides, oliogosaccarides, ammonia, very long chain fatty acids, etc.), as well as imaging studies, such as an MRI.

Step 4

If tests are negative but specific concerns persist, consideration may be given to repeating or performing additional tests. Positive metabolic tests results are sometimes more readily apparent when a child is febrile.  If there is a high index of suspicion of seizures after obtaining a negative EEG, long-term monitoring should be considered. Ophthalmologic examination may be considered in the evaluation of certain genetic and metabolic disorders.

Step 5

If all tests have been negative in the context of global developmental delays, or intellectual disability, then consideration should be given to referral to specific specialists such as child neurologist, geneticist and/or developmental pediatrician.

Step 6

If a child has undergone an unremarkable medical work-up, and even negative evaluations by specialists, periodic reassessments by genetics is often beneficial. This field is rapidly expanding as new technology becomes available.

Why is it important to perform a medical work-up to rule out associated medical conditions?

Positive findings have genetic counseling implications for families who wish to have more children, for brothers and sisters, and/or other family members. They also may provide prognostic information for certain identifiable medical conditions. Some diagnoses also mandate additional assessments and monitoring for other potential medical complications. At times, a child's developmental presentation may be idiopathic, despite comprehensive evaluations. Overall, it is important to understand that developmental and medical assessments and services for children with neurodevelopmental disorders are often ongoing. It is equally imperative that families understand the chronic nature of many developmental disorders and are well-supported in order to address these needs.

For more information about developmental-behavior pediatrics or to contact Dr. Friedman, please call (720) 777-6636.